Blanket for offset-printing presses and method of making the same.



B. W. HOERBELT.

BLANKET FOR OFFSET PRINTING PRESSES AND METHOD 0F MAKING THE SAME.

APPLICATION FILED MAY 6. I9I6.

Patented. Jan. 9, 19N..

W; f I \\\\\A\\\\\\\\\\\wm\\\\\\\m\\m`imwwmmmvx 19m mw derstood that blankets of this type are BEBNARD W. HOERBELT, OF BUFFALO, NEW YORK.

` BLNXET FOB OFFSET-PRINTING PRESSES AND METHOD 0F MAKING THE SAIE.

f narines.

To all 'whom 'it may concern Be it known that l, BERNARD W. l-l'onn- Amm, a citizen of the United States, residing printing presses,

'at Buffalo, in the county of Erie and State of New York, have invented certain new and useful improvements in Blankets for Offset-Printing Presses and Methods of Making the Same, of which the following` is a specication.

My invention relates to blankets forco'set and more particularly to rubber covered blankets used for lithographic printing. Blankets of this kind heretofore used 'were constructed ofv thin sheets of rubber backed with cotton or other textile material; but material of this nature tendsto creep under slight rolling pressure and when applied to will dip or belly at or near the middle of the cylinder of its own weight; it being unmerely clamped at their marginal portions to the osetcylinder or plate. rlhis creeping of the blanket, somewhat increased on a cylinder by reason of the dip or belly of the blanket, makes it difficult to obtain a clear and clean impression vfrom the bed or plate,

. or from the bed or plate cylinder, as the case may be. impressions taken are therefore not true tothe subject; the dots and lines of the original plate being diEerentafter the 'impression on the blanket is offset to the paperor other-substances upon which the impression is made. This is also brought about by reason of the fact that the present form of rubber covering for an odset press cannot be applied smoothly enough around the offset cylinder, which added to the shifting, owing to the softness of the rubber surface and the backing, renders offset' presses unsuitable for the finest grade of printing from plates. Moreover, the present form of blanket.

offset blanket has its surface finely pitted, which to some extent prevents clear impression being made, andl this pitted condition becomes exaggerated with the vuse of the The primary object of my invention is to provide an some of the objectionable features above mentioned are entirely eliminated, .awhileothers are lessened to a considerable extent. f A further object is to provide a blanket Y YYforoset presses having a non-stretchable or non-yielding base or baclring and a thin fac- Specication of Letters Patent.

the face of a cylinder` offset blanket by means of which rammen aan. e. ieri.

Application led May 6, 1918. Serial No. 95,805.'

ing of rubber, or other material having like qualities, mounted upon the non-stretchable or non-yielding base, preferably'by cementing the same thereto in a stretched condition.

`With these and other objects to appear hereinafter, my invention consists in an oil'- set blanket having a non-yielding'base or backing and a rubber or similar impression surface or layer -applied to said base or backing in stretched condition.

lt further consists in a blanket constructed of a non-stretchable base or backing and a thin sheet or film of rubber, or other material having like qualities, of smaller area than the base or backing stretched to cover the entire surface of the latter and cemented thereto at all points. l l.

lt further consists in the particular construction hereinafter described and claimed and in the method of'making the same.

ln the drawing,-Figure 1 is a fragmentary longitudinal section of an offset flat printing machine showing only. such parts thereof as are intimately associated with my invention. Fig. 2 is a fragmentary cross `intimately associated with my invention.

Fig. `3 is a perspective view of the two members of my preferred form showing approximately the relative sizes of the non-stretchable or non-yielding base or backing and the rubber or similar impression or facing member prior to applying the latter to said base or backing. Fig. 4 is a perspective view showing the rubber or similar facing or impression member of my blanket stretched to the size of the base or backing preparatory to cementing the same thereto. Fig. 5 is a perspective view of a complete offset blanket constructed according to my invention. Fig. 6 is a transverse section through the completed blanket, the facing member and base or backing being exaggerated in thickness toy better disclose the construction of the blanket. Figs. 7 and.

8 are transverse sections through modiied forms of blankets embodying my invention.

Reference being had to the drawing in detail, similar numerals refer to similar parts in the several fi res. n

Reference belng particularly had to Fig. 1, the numeral? designates the bed or frame of a Hat offset printing machine on which is held a block or other body 8 to which a of offset blanket Hat plate 9 is applied. This plate may be .termedA the printing device 4and may consist of types, electrotypes, etchings or ary other form of device used in the printing art, but for the finer grades of printing a thin zinc plate, such as shown in the drawing, is preferably employed. On the bed or frame af placed.

i 11 designates the blanket-covered offset cylinder which may be constructed in the usual manner. This cylinder is adapted to travel back and forth over the printing device 9 and tympan or. plate 10, and while thus traveling pass in contact with said printing device and said. tympan or plate. 0n this cylinder my improved offset blanket 12 is shown, the same being tightly fitted around the cylinder and clamped, as shown at13, or in any other suitable manner.

ln the rotary offset printing machine partly shown in Fig. 2, which is, the form of machine mostlyy used, 14 designates the bed or plate cylinderwhich is ofthe usual construction, and has the zinc printing plates 15 kapplied thereto in the usual manner. .Rotating in contact with the bed or plate cylinder. is the blanket-covered offsetv cylinder ,16. This cylinder may vbe conlstructed in the same manner as that shown in Fig. A1, or in any other suitable manner, and my nnprovedoset blanket 12 is ap-v plied to the odset cylinder 1 6 in the same manner as shown in Fig. 1.

17 designates the tympan or! printing cylinder, between which and the blanketco't'ered o setcylinder the paper or other material 1 8 is to be passed which is to receivetheimpression from the offset. 'It is of course understood that indifferent forms of rotary-offset printing'presses the three cylinders are differently arranged, and that they need not necessarily lie, in the same vertical plane,`,as;shown in Fig. 2. The

matter to be printed is transferred upon the z inc printing-'plates 9 ory 15, the process for doing which is identical with the common process of lithc'graphing` and v'is well known to thoseskilled inthe art to which this in- Vention relates. 1' Several other methods of transferring the matter to be printed upon' 'the zinc printing plates are known, and may b e used ifdesired. Y

The:l inking arrangement forthe printing plate of the flat bed offset printing machine shown in Fig.v 1, may be any of the common forms used for distributing ink over` the "faceof the plate, and -it is of course under'stood that in connection with the inking arrangementan arrangement" is A'provided for dampening the'surface of the plate, ex-

cept the transfer parts or the substances tol from the water rollers will not adhere to nor act upon'the transfer part or the substances to' be printed, owing to the greasy nature of the transfer; consequently the inking rollers passing over the platewill deposit no ink Where the plateis dampened but will ink the transfer to the required strengths. The inked up transfer then'prints upon the offset blanket 12 of the'ofset cylinder when the latter is passedY thereover, ,and in its travel forward said cylinder passes over and in contact with the paper or other material placed upon the tympan or plate 10, which material receives the impression from the rubber offset blanket.

The inking arrangement for the rotary offset printing machlne shown in Fig. 2 is not unlike that of a web press, only that the inking rollers are leather orlithographl rollers and are provided with a greater distribution than the rollers of a web press. lnking rollers of this'ln'nd may also be used on the flat bedV press shown in Fig. l, and

lthe method of dampening the printing plates of the rotary machine may be similar to that above described with reference to the flat bedmachine shown inFi 1. The inking and dampening methods, owever, form' no part of myY invention and maybe performed in any suitable way.

Reference being particularly .had to my improved blanket and the method of making the same, 19 designates the base or baeking of the blanket,- which is preferably of f sheet metal and may be zincof about the vthickness of a two-ply cardboard, -or any other thin sheet metal, and for certain classes of work I have found press-board tof be most effective. On this base or backing,

I'apply a thin sheet or film or rubber, designated by the numeral 20. This sheet or -1m of rubber is cut to a size somewhat sn'ialler than the base or backing, and preparatory to applying the samel thereto'it is carefully stretched to thevsize of the base or backing ing;' care being taken that the rubber is or film is firmly secured to the base or backevenly stretched. and that no surplus cement remains between the rubber and the base or backing. v lWhen using press-board as a base or` backing, it is rendered water-proof by saturatimg the same with oil, or any other manner thus preventing swelling of the press-boar in the event of abreak occurring in the rubusing ber covering and Water passing through and reaching the press-board.

Zinc and press-board bases or backings are non-stietchable and non-yielding, and any material having such qualities may be substituted for the zinc or press-board. The stretching of the sheet` or film of rubber eliminates all inequalities of the surface thereof, and when the rubber is applied and pressed in position on the base or backing it is perfectly smooth and to a very slight degree yielding under pressure, but not in length and Width.

As stated, for some classes of work, pressboard as a base or backing is desirable, and the degree. to which the rubber is to be stretched before applying it to the base or backing depends considerably upon the class of Work to be done. I have found from experience that different kinds of work require different blankets. `For the ordinary run of work I do not consider it necessary to stretch the rubber sheet or film to so great an extent as where finer work is to be done. The finer and sharper the work is to be, the thinner the rubber cover'or film must be and the more it should be stretched over the ,base or backing. The degree of tension applied to the work is also to be taken into consideration when applying a blanket to an offset cylinder and therefore the greater the tension applied to the blanket the stiffer should be the base or backing upon which the rubber sheet or film is mounted. It may here be stated,'however, that if the base or backing is too stiff it will not properly hug the offset cylinder' of the machine and imperfect Work would result therefrom.

Press-board I have found admirably adapted for a base or backing of blankets for certain kinds of Work, but I find that when such material it is desirable to reduce the tension on the rubber since if the tension is too great it would pull on the press-board and cause the same to be drawn away` from the oset'cylinder.

In printingfrom type it is necessary to have a very thin `film or cover applied to the base or backing and a hardbase or backing is preferable in such cases, While for the offset on what is known as litho-presses upon which the finest work is done, zinc is preferably used as a base or backing, although in most cases press-board would suffice. When printing upon rough stock and when using zinc plateshaving a deep grain, a thicker film or sheet of rubber and less stretch thereto may be used.

Aluminum, tin and other similar metallic substances of a non-yielding nature may be substituted for zinc as a base or backing for my o'set blanket, and any stretchable material possessing the qualities of rubber may be substituted for the sheet or lm of rubber.

. base or rubber stretched and cemented to Said base I have experienced that on blankets used on large presses it is desirable to provide the same with a somewhat resilient underv This resilient underlay may alsoconsist of a sheet of ordinary paper'placed against the underside of the base or backing and a sheet of blotting paper applied to said sheet of ordinary paper. This underlay therefore is positioned between the base or backing and the surface of the cylinder when the blanket is applied to the latter, and while I prefer to mount this underlay directly onto the underside of the base or backing it may be placed between the blanket illustrated in Figs. 1 tot and the cylinder, and While the mounting of the underlay on the underside of the base or backing will save considerable time in applying the blanket to the machine, both forms of underlays referred to will take up spots that would not otherwise print because of the inequalities in the zinc printing plate or other printing device. rlhis re` i silient underlay does not in any manner aHect the working surface of the blanket but merely provides the necessary resiliency to y'assure even pressure against the zinc printing plate or other printing device throughout the length of the cylinder and at all points around its circumference.

Having thus described my invention, ,what I claim is,-

1. A blanket for oset printing presses having a non-yielding base or backing and a sheet'or film of stretchable material stretched over and applied to said base or backing.

2. A blanket for oset printing presses comprising a non-stretchable base or backing and a sheet or film of stretchable materialstretched and cemented at all points to said base or backing.

3. A blanket for offset printing presses comprising a non-yielding non-stretchable backing and a thin sheet or film of or backing. 4. A blanket for oset printing presses comprising a flexible non-stretchable base or backing and a sheet or lm of stretchable material of smaller size than said base or backing stretched to the size of the latter' and cemented thereto.

5. A blanket for odset printing pressesI comprising a flexible non-stretchable base or backing and a sheet or film of stretched rubber, the two being joined together to prevent relative vmovement thereof.

v(ifAblanln'et :for offset printing'presses comprising a em'ble non-stretchable basev or backing and a sheet or lilm of stretched rubber, the two being joined together to prevent independent movement of said sheet ber on said hase or backing.

7. A blanket for oiiset printing presses comprising a emble non-stretchable base or backing and a. sheet or lm of stretched,

rubber, the two being joined together to prevent creeping of said sheet or film of rub- '8. A blanket ffor oii'set printing presses comprising a iiexibl'e non-stretchable base or hacking and a sheet or film of stretched rubber, the two being joined together to preoiiset` printing presses `which consists stretching a thin sheet or lm of rubber 'or other stretchable .material and cementing the same to one ofthe faces cf a sheet of non-stretchable material.'

11. The method of makingA blankets `for offset printing presses comprising a, base or vbacking and a covering slightly yielding under pressure, which consists' in the use of a non-stretchable base or backing and a sheet or lm of rnbber of'sinaller size thansaid base or backing,l and in stretching said sheet or hlm to the size of said base or backing and cementing the two'together.

12. Ablanket for offset printing presses having a non-yielding base or backing, a sheet or lm of '-stretchable material stretched over and applied to one side of said base or backing; and a resilient under lay applied to the. other side' of said base or backing.

13. A blanket for oiset printing presses i comprising anon-yielding non-stretchable base erbacklng, and a *sheety or1ilm of stretchable material stretched over and applied to said base or backing. l

14. A blanket for offset printing presses comprising a non-yielding base or backing,

a stretched layer or film of material applied to, one face of said base or bacln'ng, a sheet of paper applied to the other face of said hase or backing, and a sheet of yielding material applied to said sheet of paper. -V

l5. The method of makingblankets for oi'set rinting presses which consistsin stretching a thin sheet or lm ofrubber or other stretehable material and cementing the same to one of the faces f a sheet of non-stretchable non-yieldingmaterial and in applying a sheet of yielding material to the other face of said sheet of non-stretchable non-yielding material.

lx1-testimony whereof I BERNARD H OERBELT.

atiix my: signatlire. 

